Tube-perforating mechanism



Sept- 1961 c. A. MERCER TUBE-PERFORATING MECHANISM Filed Sept. 22, 1958 INVENTORV CARL A. MERCER BY 15. Jm

ATTORNEY United e P re This invention relates to mechanism for perforating metal tubing such as may be used in muiflers of automotive vehicles. An object of the present invention is to provide means that employs a single tool that both feeds a tube longi-v tudinally while the same is rotating and perforates. the tube, thereby providing means that is economical due to low buiding and-operation cost, and so simple that maintenance is greatly facilitated.

Another object of the invention is. to provide a tubeperforating mechanism that provides a. tube with uniformly arranged perforations in helical form and so spaced, cireurnferentially, that the perforations in one convolution are circumferentially offset from those of an adjacent convolution.

A further object of the invention is .to provide mechanism that forms inwardly directed perforationrdefining burrs in a continuous manner and while continuously feeding a tube. V

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawing merely shows and the following description merely describes, one embodiment of the present invention, which is given by way of illustration or example only.

In the drawing, like reference characters designate similar parts in the several views.

FIG. 1 is a broken longitudinal sectional view of tubeperforating mechanism according to the present invention.

FIG. 2 is an end view thereof as seen from the right of FIG. 1.

FIG. 3 is an enlarged and fragmentary detail view showing one view of a perforation-forming operation.

FIG. 4 is a similar view showing the operation as seen at right angles to what is shown in FIG. 3.

The present tube-perforating comprises, generally, means for guiding a tube 11 for both longitudinal and rotatory movement, a mandrel 12 over which the tube loosely fits and relative to which it moves, a rotary cutter 13 that perforates said tube and, while so doing, moves the tube both longitudinally and rotationally, and a common support 14 for said means 10 and the cutter 13.

While the support 14 is shown as separate upper and lower portions, it will be understood that the same constitute fixed portions of a machine frame so that the means 10 and the cutter 13 are relatively fixed, although rotational on their respective axes, as will later be described. A bracket 15 is afiixed to the support 14 and mounts the means 10 and a bracket 16 is afiixed to the support 14 and mounts the cutter 13.

The mandrel 12 comprises a rod that may be withdrawn endwise to allow the positioning of a tube 11 in such position as to be engaged by the guide means 10 and with the cutter 13 in substantially the manner shown. Then, before the perforating is instituted, the mandrel is replaced to form an inner but loose support for the tube.

The tube 11 is preferably steel, either seamless or seambest seen in FIG. 1.

Patented Sept. 12, 1961 welded, although other metals may be perforated by the present mechanism.

The guide means 10 is shown as a set of rollers 17 arranged to support the tube 11 in a straight path of movement, said rollers so surrounding the tube that at least the upper ones receive the force or pressure imposed by the cutter 13. Of course, the roller spacing is: such that the tube is freely rotational.

The cutter 13 is disposed on an axis of rotation 18 that is preferably approximately 30 to the horizontal, as Said cutter is so positioned that its teeth 19 successively penetrate the -wall of the tube 11 from beneathrto place the mentioned reactive pressure on the upper rollers 17 of the guide means 10. Said teeth 19 are so formed that, as seen in FIG. 3, the same are presented to the tube to form two similar inbent burrs 26, the apex 21 of each tooth being defined by opposite and similar tooth sides 22 and 23. By reason of the mentioned angle of presentation of the cutter to the tube, the side faces 22 of each cutter tooth 19 and the peripheral faces 23 thereof quite symmetrically penetrate the tube so that the burrs 20, as in FIG. 3, are formed.

. As shown in FIGS. 2 and 4, the teeth 19, as seen from the front, have said apices 21 located where a radial edge 24 and a tangential edge 25 meet. As a consequence, said teeth cut or tear into the tube 11 in a manner to form elongated perforations that are somewhat tapered, as suggested in FIG. 1. The edge 24 cuts sharply and the edge 25, as it slopes from the apex 21, cuts gradually less deeply to form such tapered perforations. As a consequence, the burrs are quite deeply inbent at one end of the perforation and fade into the wall of the tube, as in FIG. 4.

As seen in FIG. 1, the axis 18 is disposed at an angle to the plane of the figure, -i.e., said axis is at a double angle with respect to the axis of tube 11. In other words, the axis of the cutter is at an angle to the axis of the tube and also lies in a plane that is at an angle to the tube axis. In this case, said plane is vertical since the tube axis is horizontal. Therefore, the successive cutter teeth 19 do not cut circumferentially but rather helically into the tube. Since the latter is free to move endwise as well as to rotate, the tube is advanced longitudinally as the successive teeth penetrate the tube.

The helical formation of the perforations is the result of the last-mentioned angular displacement of the axis 18 at an angle to the vertical plane in which the tube axis resides. The perforations are also ofiset so that longitudinal rows thereof are non-parallel to the tube axis. This is brought about by having the perforation spacings, circumferentially, difierent than equal incremental spacings of the tube surface. Thus, no adjacent perforations are on a longitudinal or axial line, a feature important in mufiier construction. 7

It will be understood that only the cutter 13 is driven, the drive being in the direction of arrows 26. Any suitable rotative power may be applied to shaft 27 of the cutter to perform the tube-perforating operation above described.

While the foregoing specification illustrates and describes what I now contemplate to be the best mode of carrying out my invention, the construction is, of course, subject to modification without departing from the spirit and scope of my invention. Therefore, I do not desire to restrict the invention to the particular form of construction illustrated and described, but desire to cover all modifications that may fall within the scope of the appended claims.

Having thus described my invention, what I claim and a am cutter having circumferentially arranged teeth, each tooth being formed to have a radial edge and a tangential edge that meet to form a penetrating apex, said cutter being disposed at an angle with its axis of rotation a vertical plane and at an angle to the horizontal, the T- tation of the cutter being in a direction advancing the teeth with the tangential edges thereof leading, and

means to guide a tube along a horizontal path that lies in a vertical plane that is at an angle to the mentioned vertical plane, the successive teeth of the cutter penetrating the tube to simultaneously rotate and longitudinally advance the tube, thereby producing perforations in the tube that are arranged on a helix, the mentioned tooth edges imparting an elongated taper form to said perforations.

2. Tube-perforating means according to claim 1 in which the tube-guiding means comprise an inner mandrel over which the tube is loosely fitted, and outer tube-en gaging rollers on axes stationarily mounted and parallel series of teeth formed in the edge thereof; a shaft on which the cutter is mounted, said cutter engaging'the outside of the tube and forming perforations through the wall thereof; and mounting means for the cutter shaft effective to maintain the axis thereof at an angle to the axis of the tube in both vertical and horizontal planes, the teethofthe cutter acting-to form a helically arrangedseries of perforations in the wall of the tube due to the simultaneous displacement in longitudinal rotational direction of the tube about its axis caused by the teeth ofthecutter Y 4. Tube-perforating mechanism as set forth in claim 3 and in which said stationary guide means for the tube workpiece include: a stationary mandrel projecting into and loosely fitting in said tube.

5 Tube-perforating mechanism according to claim 3 in which the cutter teeth each" have an apex that penetrates the wall of the tube and inwardly displaces perforation-defining burrs.

1,051,803 Cardell Jan. 28, 1913 1,061,979 Burton May 20, 1913 1,536,924 Pierce May 5, 1925 1,736,955 Welsh Nov. 26, 1929 1,865,301 Bunker June 28, 1932 1,909,868 Pearlman May 16, 1933 2,185,337 Green Jan. 2, 1940 r 2,217,327 Zeidler Oct. 8, 1940.

2,599,857 'Mildner June 10, 1952 2,661,579

6. Tube-perforating mechanism according to claim 5 in which'the guide means include stationarily mounted tube-supporting rollers.

References Cited in the file of this patent UNITED STATES PATENTS Lomazzo et al. Dec. 8, 1953 

